Preparation and 3D printing of high-thermal-conductivity continuous mesophase-pitch-based carbon fiber/epoxy composites

To meet the requirements of spacecraft for the thermal conductivity of resins and solve the problem of low thermal conduction efficiency when 3D printing complex parts, we propose a new type of continuous mesophase-pitch-based carbon fiber/thermoplastic polyurethane/epoxy (CMPCF/TPU/epoxy) composite filament and its preparation process in this study. The composite filament is based on the high thermal conductivity of CMPCF, the high elasticity of TPU, and the high-temperature resistance of epoxy. The tensile strength and thermal conductivity of the CMPCF/TPU/epoxy composite filament were tested. The CMPCF/TPU/epoxy composites are formed by 3D printing technology, and the composite filament is laid according to the direction of heat conduction so that the printed part can meet the needs of directional heat conduction. The experimental results show that the thermal conductivity of the printed sample is 40.549 W/(m·K), which is 160 times that of pure epoxy resin (0.254 W/(m·K)). It is also approximately 13 times better than that of polyacrylonitrile carbon fiber/epoxy (PAN-CF/epoxy) composites. This study breaks through the technical bottleneck of poor printability of CMPCF. It provides a new method for achieving directional thermal conductivity printing, which is important for the development of complex high-performance thermal conductivity products.